1. Field of the Invention
This invention relates to optical fiber centering devices and, in particular, to such devices which provide alignment of an optical fiber with high accuracy so as to be suitable for use in numerous fiber coupling designs. Accordingly, it is a general object of this invention to provide new and improved devices of such character.
2. Description of the Prior Art
Various techniques were used in the past to center optical fibers. Such techniques, as known, utilized either (1) micromanipulators to initially align an optical fiber either manually or servomechanically before applying epoxy to fix the fiber in place; (2) precision machined holes, or ferrules, in conjunction with epoxying, soldering or crimping; or, (3) watch jewels, often requiring several in tandem, followed by epoxying or crimping.
In the foregoing methods, highly accurate, usually expensive parts were required. Micromanipulators, moreover, could be used only in a laboratory environment or its equivalent. Human or servomechanical adjustment was required and the optical fiber had to be held precisely in place during the epoxy curing time. Machined metal parts used in some connectors required extreme machining accuracy and, hence, were expensive to use. Machined holes and jewels had to be sufficiently large to accept all fiber diameters within a manufacturer's tolerance range, and, therefore, tended to be loose fits for most fibers.
The following three patents were cited during the course of prosecution of applicants' parent application: U.S. Pat. No. 4,181,401 to Jensen, issued Jan. 1, 1980, U.S. Pat. No. 4,201,443 to Hodge, issued May 6, 1980 and U.S. Pat. No. 4,257,674 to Griffin et al., issued Mar. 24, 1981.
U.S. Pat. No. 4,181,401 to Jensen relates to fiber optic waveguide connectors employing a plurality of radially adjustable jaw members. Though Jensen illustrates three jaw members and an aluminum housing having an axially directed bore therein, the Jensen device including solely the jaw members and housing is incapable of centering an optical fiber. Jensen recognizes such incapability by providing a plurality of adjustment screws and associated tapped bores for necessary alignment. Without such adjustment screws by Jensen, centering of optical fibers would be reliably uncertain. Furthermore, there is no suggestion therein to substitute a force fit for the jaws in lieu of the loose adjustable fit with screws disclosed in Jensen. It is further noted that Jensen, illustrating metallic members, does not suggest elastomeric material.
U.S. Pat. No. 4,201,443 to Hodge, which illustrates an optical fiber coupler comprising a guide assembly having three glass rods disposed in a side-by-side array parallel to one another, was cited as of interest in the parent application to show three cylindrical jaws for clamping an optical fiber.
U.S. Pat. No. 4,257,674 to Griffin et al. relates to an elastomeric fiber optic splice and, but for its citation, does not appear to be pertinent.
3. Discussion of Other Art
In two copending U.S. patent applications, one by W. John Carlsen entitled "METHODS OF AND APPARATUS FOR CONNECTING OPTICAL FIBERS", Ser. No. 23,862, filed Mar. 26, 1979, now U.S. Pat. No. 4,325,607, issued Apr. 20, 1982, and the other by W. Griffin, W. John Carlsen and J. E. Benasutti entitled "ELASTOMERIC FIBER OPTIC SPLICE", Ser. No. 32,583, filed Apr. 23, 1979, now U.S. Pat. No. 4,257,674, issued Mar. 24, 1981, there are described fiber optic splices which were designed to precisely align automatically two fibers along the same axis so as to optimize power transfer between them. The instant invention, however, is intended to precisely align a single fiber automatically along an externally defined axis.
In a third copending U.S. patent application by W. John Carlsen entitled "OPTICAL FIBER CONNECTORS", Ser. No. 112,991, filed Jan. 17, 1980, there is described telecentric fiber optic connectors using plastic molded optics. Alignment is achieved by utilizing a variation of the splice configuration shown in U.S. Pat. No. 4,325,607, wherein accuracy of the mold and molding process provide a precise centering.